Stabilized distillate fuel oil



United Statcs Patent Ofi 3,095,286 Patented June 25, 1963 ice 3,095,286STABILIZED DISTILLATE FUEL 01L Harry J. Andress, Jr., Pitman, and PaulY. C. Gee, Woodbury, NJ., assignors to Socony Mobil Oil Company, Inc., acorporation of New York No Drawing. Filed May 7, 1958, Ser. No. 733,4844 Claims. (Cl. 44-71) This invention relates to the improvement ofnonlubricating petroleum fractions. It is more particularly concernedwith distillate fuel oils containing additives adapted to inhibit theappearance of sediment during prolonged storage periods, to preventscreen-clogging, and to prevent rusting of ferrous metal surfaces.

It is well known that fuel oils are prone to form sludge or sedimentduring periods of prolonged storage. This sediment, of course, has anadverse effect on burner operation, because it has a tendency to clogscreens and nozzles. In addition to sediment formed during storage, mostfuel oils contain other impurities, such as rust, dirt, and entrainedwater. The sediment and impurities tend to settle out on equipmentparts, such as nozzles, screens, filters, etc, thereby clogging them andcausing the equipment to fail.

A further factor, incident to the storage and handling of fuel oils, isthe breathing of storage vessels. This results in the accumulation ofconsiderable amounts of water in the tanks, which presents a problem ofrusting in the tanks. Then, when the oil is removed for transportation,sufficient water may be carried along to cause rusting of ferrous metalsurfaces in pipelines, tankers, and the like.

Generally, it has been the practice to overcome the aforedescribeddifiiculties with a separate additive for each purpose, i.e., with asediment inhibitor, an antiscreen clogging agent, and an antirust agent.The use of several additives, however, gives rise to problems ofadditive compatibility, thus restricting the choice of additivecombinations. In addition, of course, the use of a piurality ofadditives unduly increases the cost of the fuel. It has been proposed toovercome two difliculties, e.g., sedimentation and screen clogging, withone additive. Insofar as is known, however, no single addition agent hasbeen found effective against sedimentation, screen and nozzle clogging,and rusting of ferrous metal surfaces.

' It has now been found that all three problems, i.e., sedimentation,screen clogging, and rusting, can be solved by the use of a single fueloil addition agent. It has been discovered that a distillate fuel oilcontaining minor amounts of certain amic acids and amine salts thereofis effectively inhibited, simultaneously, against all threeaforementioned difliculties.

Accordingly, it is a broad object of this invention to provide a fueloil having properties improved with a minimum number of addition agents.Another object is to provide a fuel oil having a single additive adaptedto inhibit sedimentation, to prevent screen clogging, and to preventrusting of ferrous metal surfaces with which it comes in contact. Aspecific object is to provide a fuel oil that contains certain amicacids or amine salts thereof that achieve these results. Other objectsand advantages of this invention will become apparent to those skilledin the art from the following detailed description.

The present invention provides a distillate fuel oil containing a minoramount, sufficient to inhibit sedimentation and screen clogging and toprevent rusting of ferrous metal surfaces in contact therewith, of acompound selected from the group consisting of (1) a phthalamic acidhaving the formula:

.(J}=Q NHR wherein R is a monovalent aliphatic hydrocarbon radicalhaving between about 4 and about 30 carbon atoms; (2) atetrahydrophthalamic acid having the formula:

on, 0 on cH-iiorr i'lH JH-G=0 o i NHR wherein R is a monovalentaliphatic hydrocarbon radical having between about 4 and about 30 carbonatoms; (3) a hexahydrophthalamic acid having the formula:

CH: 0 (iii, on-hon 0H; OBI-(i=0 orn t tan wherein R is a monovalentaliphatic hydrocarbon radical having between about 4 and about 30 carbonatoms; (4) a nadamic acid having the formula:

I OH NHR wherein R is a monovalent aliphatic hydrocarbon radical havingbetween about 4 and about 30 carbon atoms; and (5) the salts of (l),(2), (3), and (4) with aliphatic primary amines having between about 4and about 30 carbon atoms per molecule.

The addition agents utilizable in the fuel oil compositions of thisinvention are the amic acids that have the formulae:

wherein R, in each case, is an aliphatic hydrocarbon radical of analiphatic primary amine having between about 4 and about 30 carbon atomsper radical, and the amine salt of those amic acids with an aliphaticprimary amine having between about 4 and about 30 carbon atoms permolecule. The amic acids contemplated herein can be made by any methodfor preparing such compounds that is known to the art. They areproduced, preferably, by warming equimolar amounts of phthalic acidanhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic acidanhydride, or nadic acid anhydride, respectively, and an aliphaticprimary amine having between about 4 and about 30 carbon atoms permolecule to form the monoamide of the acid. This can be done readily byheating the mixture of anhydride and amine at a temperature of 65-150 C.for a period of time varying between one and three hours. The additionoccurs readily without the formation of water. Less desirably, the amicacids can be prepared by the controlled reaction between phthalic acid,tetrahydrophthalic acid, hexahydrophthalic acid, or nadic acid and theamine, with the elimination of one mole of water per mole of amic acidproduced. Care must be exercised, however, to avoid the elimination oftwo moles of water to form the cyclic imide. Regardless of the methodused to form the amic acid, the salt thereof can be made readily bywarming equimolar quantities of the amic acid and an aliphatic primaryamine having between about 4 and about 30 carbon atoms per molecule. Thesalt-forming amine can be the same amine used in making the amic acid,or it can be a different amine. In the case where the salt-forming amineis the same used in the amic acid, the salt can be made by heating twomoles of amine with one mole of acid anhydride under temperatureswhereby water is not evolved.

The amines utilizable in forming the amic acids and the salts thereofare the primary aliphatic amines having between about 4 and about 30carbon atoms per molecule. These are the monoamines having a single openchain hydrocarbon group attached to a nitrogen atom. The aliphaticradical can be saturated or unsaturated, and branched-chain or normalchain. Likewise mixtures of these amines, as well as pure amines, can beemployed. A very useful and readily available class of primary aminesare the tertiaryalkyl, primary, monoamines in which a primary amino(--NH group is attached to a tertiary carbon atom; and mixtures thereof.These amines all contain the terminal group,

CH| -til-NH:

Non-limiting examples of the amine reactants are t-butyl amine, n-butylamine, t-hexyl primary amine, n-hexylamine, n-octylamine,n-octenylamine, t-octyl primary amine, Z-ethylhexylamine, t-decylprimary amine, n-decylamine, t-dodecyl primary amine, n-undecylamine,dodecenylamine, dodecadienylamine, tetradecylamine, t-tetradecyl primaryamine, t-octadecyl primary amine, hexadecylamine, octadecenylamine,octadecadienyl amine, t-eicosyl primary amine, t-docosyl primary amine,t-tetracosyl primary amine, and t-triacontyl primary amine. The aminereactants can be prepared in several ways well known to those skilled inthe art. Specific methods of preparing the t-alkyl primary amines aredisclosed in the Journal of Organic Chemistry, vol. 20, page 295 et seq.(1955). Mixtures of such amines can be made from a polyolefin fraction(e.g., polypropylene and polybutylene cuts) by first hydrating withsulfuric acid and water to the corresponding alcohol, converting thealcohol to alkyl chloride with dry hydrogen chloride, and finallycondensing the chloride with ammonia, under pressure, to produce at-alkyl primary amine mixture.

The fuel oils that are improved in accordance with this invention arehydrocarbon fractions having an initial boiling point of at least about100 F. and an end boiling point no higher than about 750 F., and boilingsubstantially continuously throughout their distillation range. Suchfuel oils are generally known as distillate fuel oils. It is to beunderstood, however, that this term is not restricted to straight-rundistillate fractions. The disillate fuel oils can be straight-rundistillate fuel oils, catalytically or thermally cracked (includinghydrocracked) distillate fuel oils, or mixtures of straight-rundistillate fuel oils, naphthas and the like, with cracked distillatestocks. Moreover, such fuel oils can be treated in accordance with wellknown commercial methods, such as, acid or caustic treatment,hydrogenation, solvent refining, clay treatment, etc.

The distillate fuel oils are characterized by their relatively lowviscosities, pour points, and the like. The principal property whichcharacterizes the contemplated hydrocarbons, however, is thedistillation range. As

mentioned hereinbefore, this range will lie between about 100 F. andabout 750 F. Obviously, the distillation range of each individual fueloil will cover a narrower boiling range falling, nevertheless, withinthe abovespecified limits. Likewise, each fuel oil will boilsubstantially continuously throughout its distillation range.

Particularly contemplated among the fuel oils are Nos. 1, 2, and 3 fueloils used in heating and as diesel fuel oils, and the jet combustionfuels. The domestic fuel oils generally conform to the specificationsset forth in ASTM Specifications D396-48T. Specifications for dieselfuels are defined in ASTM Specifications D975-48T. Typical jet fuels aredefined in Military Specification MlL-F-5624B.

The amount of phthalamic acid or amine salt of phthalamic acid additivesthat is added to the distillate fuel oil in accordance with thisinvention will depend, of course, upon the intended purpose and theparticular amic acid or salt selected, as they are not all equivalent intheir activity. Some may have to be used in greater concentrations thanothers to be effective. In most cases, in which it is desired to obtainall three beneficial results, namely, to inhibit sedimentation, toreduce screen clogging, and to prevent rusting of ferrous metalsurfaces, additive concentrations varying between 10 pounds per thousandbarrels of oil and about 200 pounds per thousand barrels of oil will beemployed. It may not always be desired, however, to accomplish all threeaforementioned results. In such cases, where it is desired to effectonly one or two results, lower concentrations can be used. Thus, if itis desired only to prevent rust under dynamic conditions, as in apipeline, it has been found that concentrations as low as about 5p.p.m., i.e., about one pound of additive per thousand barrels of oil,are effective. In general, therefore, the amount of amic acid or ofamine salt of amic acid that can be added to the distillate fuel oil, inorder to achieve a beneficial result, will vary generally between aboutone pound per thousand barrels of oil and about 200 pounds per thousandbarrels of oil. Preferably, it will vary between about 10 pounds andabout 200 pounds per thousand barrels of oil.

If it is desired, the fuel oil compositions can contain other additivesfor the purpose of achieving other results. Thus, for example, there canbe present foam inhibitors and ignition and burning quality improvers.Examples of such additives are silicones, dinitropropane, amyl nitrate,metal sulfonates, and the like.

The following specific examples are for the purpose of illustrating thefuel oil compositions of this invention, and of exemplifying thespecific nature thereof. It is to be strictly understood, however, thatthis invention is not to be limited by the particular additives and fueloils, or to the operations and manipulations described therein. Otheramic acids or amine salts thereof and fuel oils, as discussedhereinbefore, can be used, as those skilled in the art will readilyappreciate.

AMIC ACIDS AND SALTS The amine reactants used in the specific workingexamples are mixtures of pure amines. Amine A is a mixture of primaryamines having a carbon atom of a tertiary butyl group attached to theamino (--NH;,) group and containing 12 to 15 carbon atoms per aminemolecule and averaging 12 carbon atoms per molecule. This mixturecontains, by weight, about percent tertiary dodecyl amine, about 10percent tertiary pentadecyl amine, and relatively small amounts, i..e,less than about 5 percent of amines having less than 12 or more than 15carbon atoms.

Amine B is a mixture of normal aliphatic primary amines containing, byweight, 10 percent hexadecyl amine, 10 percent octadecyl amine, 35percent octadecenyl amine, and 45 percent octadecadienyl amine.

Example I A mixture of 100 grams (0.5 mole) of Amine A, 74 grams (0.5mole) of phthalic acid anhydride, and 90 grams xylene, as a diluent, washeated with stirring at 65 C. for 3 hours to form the Amine A phthalamicacid.

Example 2 V A mixture of 150 grams (0.5 mole) of Amine B and 74 grams0.5 mole) of phthalic acid anhydride was heated at 80-8$ C. withstirring for 3 hours to form the Amine B phthalamie acid. 7

Example 3 A mixture of 50 grams (Ms mole) of Amine B, 24.7 grams /6mole) of phthalic acid anhydride, and 125 grams of xylene diluent wasstirred at 75 C. for 1.5 hours to form the Amine B phthalamic acid. Atroom temperature 50 grams /6 mole) of Amine B was added to this amicacid. The mixture was heated with stirring at 75- 80 C. for 1.5 hours toform the Amine B salt of the Amine B phthalamic acid.

Example 4 A mixture of 100 grams (0.5 mole) of Amine A, 76 grams (0.5mole) of tetrahydrophthalic anhydride and 176 grams of xylene diluentwas stirred at 100 C. for three hours to form the tetrahydrophthalamicacid.

Example 6 A mixture of 100 grams (0.5 mole) of Amine A, 77 grams (0.5mole) of hexahydrophthalic auhydride and 177 grams of xylene diluent wasstirred at 100 C. for three hours to form the hexahydrophthalamic acid.

Example 7 A mixture of 100 grams (0.5 motored Alanine A, 82 grams (0.5mole) of nadic anhydride aand"l82 grams of xylene diluent was stirred at100 C. for three hours to form the nadic'amic acid;

SEDIMENTATI ON The test used to determine the sedimentationcharacteristics of the fuel oils is the l00 F. storage test. In thistest, a Still-milliliter sample of the fuel oil under test is placed ina eonveeted oven maintained at 110 F. for a period of 12 weeks. Then,the sample is removed from the oven and cooled. The cooled sample isfiltered through a tared asbestos filter (Gooch crucible) to removeinsoluble matter. The weight of such matter in milligrams is reported asthe amount of sedimentation. A sample of the blanhuninhibited oil is runalohg'with a fuel oil blend under test. The efiective'ness ofa fuel oilcontaining an inhibitor is determined by comparing the weight ofsediment formed in the inhibited oil with that formed in the uninhibitedoil.

' Example 8 The additives described in Examples 1, 3, and 4 were blendedin a test fuel oil and the blends were subjected to the 110 F. storagetest. The test results comparing the blended fuels and uninhibited fuelsare set forth in Table I. The test fuel oil is a blend of 60 percentdistillate stock obtained from continuous catalytic cracking and 40percent straight-run distillate stock. It has a boiling range of betweenabout 320 F. and about 640 F. and is a typical No. 2 fuel oil.

Similarly, the additives described in Examples 5, 6, and 7 were blendedin a test fuel oil and subjected to the storage test. Results are setforth in Table I. The test fuel in this case, was the fuel described inthe preceding paragraph that had been bydrodesulfurized.

TABLE I. F. STORAGE TEST-12 WEEKS Inhibitor Inhibitor Concn, SediExample lb./l.000 merit,

Acid Anhydride Amie Salt bols. ing/liter Amine Amine blanlr 0 24{Phthalimu A 25 1a and: B B 0 50 Phthahc 100 blank, B B 0 25 Phthallc100 13 blank 0 5 'letrahydro- A 25 3 phthalic. blank 0 5 Hexahydro- A 252 H h al 0 5 urn-131 Nadir: A 2a 2 Amine combined with nnhydrlde to formthe amle acid. sminsuscd to form salt of the axnlc acid.

SCREEN CLOGGING The anti-screen clogging characteristics of a fuel oilwere determined as follows: The test is conducted using a Sun'dstrand V3or S1 home fuel oil burner with a self-contained IOO-mesh Monel metalscreen. About 0.05 percent, by weight, of naturally-formed fuel oilsediment, composed of fuel oil, water, dirt, rust, and organic sludge ismixed with 10 liters of the fuel oil. This mixture is circulated by thepump through the screen for 6 hours. Then, the sludge deposit on thescreen is Wished oil with normal pentane and filtered through a taredGooch crucible. Attcr drying, the material in Gooch crucible is washedwith aSG-SO (volume) acetonemethanol mixture. The total organic sedimentis obtained by evaporating the pentane and the acetone-methanolfiltrates. Drying and weighing the Gooch crucible yields the amount ofinorganic sediment. The sum of the organic and inorganic deposits on thescreen can be reported in milligrams recovered or converted into percentscreen clogging.

Example 9 Using the test fuel oil described in the first paragraph ofExample 8, blends of the additives of Examples 2, 3, 5, 6, and 7 in thisfuel were prepared. Each blend was subjected to the screen cloggingtest, as aforedescribed. Test results are set forth in Table II.

TABLE II.SCREEN CLOGGING Cone'n, Screen Additive of Example 1135.11.000Clogging.

.b-ols. Percent Blank 0 100 100 14 I00 14 25 I6 50 54 25 27 RUSTING Themethod used for testing anti-rust properties of the fuel oils was theASTM Rust Test D-665 operated for 48 hours at 80 F. using distilledwater. This is a dynamic test that indicates the ability to preventrusting of ferrous metal surfaces in pipelines, tubes, etc.

Example 10 Blends of the additives described in Examples 1, 2, and 3 inthe fuel oil of Example 9 were subjected to the ASTM Rust Test D-665.Pertinent data are set forth in Table III.

It will be apparent, from the data set forth in Tables I through III,that the amic acids of this invention and amine salts thereof are highlyeffective to reduce sedimentation and screen clogging and to inhibitrusting of ferrous metal surfaces. As it is to be expected results willvary among specific materials used. In order to accomplish any givenimprovement, many of the additives can be used in relatively smallamounts, as for dynamic rust prevention. If, on the other hand, it isdesired to accomplish all the aforementioned beneficial results, thiscan be accomplished at the practical additive concentration of 50-100pounds per thousand barrels of fuel oil.

Although the present invention has been described with preferredembodiments, it is to be understood that modifications and variationsmay be resorted to, without departing from the spirit and scope of thisinvention, as those skilled in the art will readily understand. Suchvariations and modifications are considered to be within the purview andscope of the appended claims.

What is claimed is:

1. As a new liquid composition, a petroleum distillate fuel oil havingan initial boiling point of at least about 100 F. and an end boilingpoint no higher than about 750 F. containing between about one pound andabout 200 pounds, per thousand barrels of fuel and suflicient to inhibitsaid fuel oil against screen clogging and sedimentation, of a compoundfrom the group consisting of (1) a phthalamic acid having the formula:

O=O in wherein R is a mixture of aliphatic hydrocarbon radicals havingbetween about 12 and about 18 carbon atoms and (2) salts of saidphthalamic acid with an aliphatic primary amine having between about 4and about 30 carbon atoms per molecule.

2. As a new liquid composition, a distillate fuel oil having an initialboiling point of at least about 100 F. and an end point no higher thanabout 750 F.; containing between about 10 pounds and about 200 pounds,per thousand barrels of fuel and suflicient to inhibit said fuel oilagainst screen clogging and sedimentation, of a phthalamic acid havingthe formula:

wherein R is a mixture of alkyl radicals having a tertiary carbon atomattached to the nitrogen atom, said mixture being about weight percenttertiary dodecyl, about 10 weight percent tertiary pentadecyl, and lessthan 5 weight percent tertiary alkyl radicals having less than 12 andmore than 15 carbon atoms.

3. As a new liquid composition, a distillate fuel oil having an initialboiling point of at least about F. and an end boiling point no higherthan about 750 F. containing between about one pound and about 200pounds, per thousand barrels of fuel and sufiicient to inhibit said fueloil against screen clogging an'd sedimentation, of a phthalamic acidhaving the formula:

in wherein R is a mixture of normal aliphatic radicals containing, byweight, about 10 percent hexadecyl, about 10 percent octadecyl, about 35percent oetadecenyl, and

about 45 percent octadecadienyl.

4. As a new liquid composition, a distillate fuel oil having an initialboiling point of at least about 100 F. and an end boiling point nohigher than about 750 F. containing between about one pound and about200 pounds, per thousand barrels of fuel and suflicient to inhibit saidfuel oil against screen clogging and sedimentation, of an amine salt ofa phthalamic acid having the formula:

0 -HNHaR rims. wherein R is a mixture of normal aliphatic radicalscontaining, by weight, about 10 percent hexadecyl, about 10 percentootadecyl, about 35 percent octadecenyl, and about 45 percentoctadecadienyl.

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1. AS A NEW LIQUID COMPOSITION, A PETROLEUM DISTILLATE FUEL OIL HAVINGAN INITIAL BOILING POINT OF AT LEAST ABOUT 100*F. AND AN END BOILINGPOINT NO HIGHER THAN ABOUT 750*C. CONTAINING BETWEEN ABOUT ONE POUND ANDABOUT 200 POUNDS, PER THOUSAND BARRELS OF FUEL AND SUFFICIENT TO INHIBITSAID FUEL OIL AGAINST SCREEN CLOGGING AND SEDIMENTATION, OF A COMPOUNDFROM THE GROUP CONSISTING OF (1) A PHTHALAMIC ACID HAVING THE FORMULA: